Continuity in iOS 8 and OS X Yosemite: Explained

Continuity is a new feature in iOS 8 and OS X Yosemite that allows iPhone, iPad, and Mac to remain true to their form-factors while still working seamlessly together. Continuity includes a new, cross-compatible AirDrop, a new Instant Hotspot for effortless tethering, Handoff to pass app activities back and forth between devices, and the ability to take and make calls and SMS/MMS from your iPhone on your iPad or Mac.